Researchers hope that a study detailing the four stages of human sperm stem cell development may shed light on infertility and certain cancers.

The study is the first to look at sperm stem cell maturation specifically in humans, says the study team.

'This information yields new insights into how sperm stem cells function and develop under normal circumstances,' said Dr Bradley Cairns, lead study author at the Huntsman Cancer Institute at the University of Utah in Salt Lake City. 'We have built a very important framework we can now use to help us understand what happens when things go wrong, resulting in issues like infertility and cancer in men.'

The team examined the gene expression profile of sperm stem cells during development. They identified four distinct phases: starting with a 'quiescent' state, to a 'proliferation' state when stem cells divide, to a 'differentiation' state when they mature to become sperm.

Most notably the study found distinct transitions in factors that influenced the different cellular states including cell cycle regulators, transcription factors, and signalling factors.

The researchers suggest their findings may also help in the understanding of certain cancers. For example, men with infertility are at higher risk of testicular and prostate cancers.

'Our study sheds new light on how genes normally function in sperm stem cells,' said Dr Cairns. 'The next steps will be to use this knowledge to better understand what changes happen when sperm stem cells don't develop normally and instead convert into cancer cells.'

While media reports regularly remind us of women's biological clocks and warn of the dangers of women leaving it 'too late' to have children, until recently little attention has been paid to the role of men in timing when to have children, and the effect of age on male fertility...